Various types of apparatus are known for the continuous production of tubes or pipes and the like and for the application of reinforcing filament or the like thereto. Some such devices and apparatus are to be found in U.S. Pat. Nos. 3,336,176; 3,429,758; 3,458,146; 3,769,127; 3,616,072; and 4,028,164.
J. Montagut in U.S. Pat. No. 4,028,164 discloses a process and apparatus for forming an elongated hollow body from fibre-reinforced synthetic resins. This patent described that a plurality of resin impregnated support fibres are positioned over and extend longitudinally along a rotating mandrel. These fibres are fed from a station having a plurality of spools thereon with the feed station rotating synchronously with the mandrel. The longitudinal support fibres form a fibrous substructure which rotates with the mandrel. A plurality of fibrous elements, which are also resin impregnated, are wrapped around the fibrous substructure to form a hollow body, which is gripped by a clamping device for pulling the same and thereby displaying the same longitudinally along the mandrel.
In U.S. Pat. No. 3,616,072 R. Bostrom discloses a machine for the continuous manufacture of reinforced plastic pipe by winding rovings soaked in uncured or partially cured resin about a tubular plastic extrusion that advances axially over a mandrel. The rovings are supplied from cakes each of which is automatically replaced when it runs out by a spare cake. Fresh cakes may be automatically supplied from a stock of cakes and separate stations may be provided.
W. Goldsworthy et al disclose in U.S. Pat. No. 3,769,127 a device for making filament reinforced tubular products in continuous manner. The device includes a series of filament spools and filament from these spools is impregnated with resin and passed around a fixed mandrel to form longitudinal strands. The mandrel extends through a plurality of helical filament wrap devices which are designed to apply opposing helically wound strands of filament upon the longitudinal strands to constitute hoop windings thereon. The mandrel further extends through circumferential filament wrap devices for laying outermost surface circumferential strands in opposite directions with respect to each other.
In my earlier U.S. Pat. No. 3,336,176 I disclose a method for producing a continuous length of reinforced thermosetting plastic conduit comprising forming a synthetic resin liner over a mandrel, providing a lubricating film between the mandrel and the liner so that the liner may be advanced freely in the direction of the axis of the mandrel and applying continuous lengths of filament longitudinally and helically on the liner to form a laminate structure. I further disclose passing the laminate structure through a vacuum chamber wherein the pressure is reduced to remove interstitial air from the laminate structure, which is then passed through a chamber containing resin under positive pressure in order to impregnate the filament structure with resin. The resin is then cured and the cured resin impregnated laminate structure is then removed from the mandrel.
None of the aforegoing patents and techniques or apparatus provide for hoop winding a cylindrical member in the advantageous manner to be disclosed hereinbelow.